Urticaria is characterised by weals (hives) or angioedema (swellings, in 10%) or both (in 40%). There are several types of urticaria. The name urticaria is derived from the common European stinging nettle ‘Urtica dioica’.
A weal (or wheal) is a superficial skin-coloured or pale skin swelling, usually surrounded by erythema (redness) that lasts anything from a few minutes to 24 hours. Usually very itchy, it may have a burning sensation.
Angioedema is deeper swelling within the skin or mucous membranes, and can be skin-coloured or red. It resolves within 72 hours. Angioedema may be itchy or painful but is often asymptomatic.
Urticaria is also known as ‘nettlerash’ or ‘hives’. It consists of wheals – spots or patches of raised red or white skin – each of which usually clears away in a few hours, to be replaced by other fresh wheals. The wheals are usually itchy, painful or cause a burning sensation. It sometimes occurs together with swelling of various parts of the body (angioedema) – typically the face, hands and feet, although anywhere may be affected.
Urticaria is very common and affects one person in five sometime in their lives. In most people, it settles quickly and is no more than a mild inconvenience, but it can be severe, longlasting and troublesome in some cases.
Urticaria is often thought to be due to allergy, but in fact, allergy is not a common cause of urticaria.
Mild transient urticaria may occur in some people in infection, or after excessive exposure to sunlight or UV light.